Why Dietary Choices Can Reduce the Risk of Cardiovascular Disease
By Chloe Arzy
From a society that was once centered around home-cooked and sit-down meals, we have progressively adopted a lifestyle of ultra-processed foods and working lunches. In turn, even though these newfound habits have increased US work productivity, they have taken a toll on our health as a society. Epidemiological evidence suggests that the increased consumption of highly processed, “inflammatory” foods have been one of the leading contributors to the continually rising incidence of cardiovascular disease (CVD) in the last 25 years. CVD is the leading cause of death in Western countries and accounts for approximately 30% of deaths worldwide.
“Data obtained in 2013 showed that the leading global cause of death in Western countries is cardiovascular disease (CVD), accounting for 17.3 million of all deaths worldwide per year.”
CVD is characterized by a spectrum of disorders that disrupt functions of the heart and blood vessels. Such disorders include hypertension (high blood pressure), atrial fibrillation, stroke, atherosclerosis, peripheral artery disease, and other vascular diseases. Oftentimes, CVD is associated with co- morbidities such as high blood pressure, type 2 diabetes, obesity, and dyslipidemia. Thus, the increasing prevalence of CVD and associated co-morbidities have led to a call for action; CVD is denoted as a public health priority and implementing preventative practices, are highly emphasized through lifestyle interventions to decrease its prevalence.
The likelihood of developing CVD is strongly correlated with lifestyle habits, including lack of regular exercise and unhealthy dietary patterns. There is an extensive scientific literature which shows that an excessive intake of sodium, added sugars, ultra-processed foods, including cured meats, and unhealthy fats can increase one’s risk for developing CVD. These foods aggregate an inflammatory diet, which is one that is associated with a widespread low grade immune system activation in the heart and other organs. Measuring such inflammation in the body can be done by measuring cellular biomarkers such as cytokines, activated monocytes, chemokines, and such molecules as C-reactive protein, fibrinogen, and serum amyloid alpha. In turn, key inflammatory pathways involve pro-inflammatory cytokine production and oxidative stress. For example, atherosclerosis is an inflammatory disease of the blood vessels involving the secretion of pro-inflammatory cytokines, and if it affects the coronary arteries is a leading cause of heart attacks. In this case, the arterial walls accumulate lipids and lipid-laden macrophages along with other cell types which can lead to chronic inflammation, stiffening of blood vessels and buildup of plaques inside the arterial walls. What has been learned from an extensive body of research is the insight that when dietary and lifestyle interventions are not implemented on a regular basis, individuals put themselves at a higher risk of developing CVD.
In an effort to mitigate the development of CVD, the implementation of a Mediterranean- style diet has shown to be a successful dietary intervention while also reducing the risk of other co-morbidities. According to a systematic review and meta-analysis of 40 randomized trials including 35,548 participants, the authors concluded that “the Mediterranean dietary pattern was superior to minimal intervention for prevention of all-cause death” and superseded five other dietary patterns tested: very low fat, modified fat, combined low fat/low sodium, Ornish, and the Pritikin diet.
The Mediterranean diet, consisting of a largely plant-based (at least 75% of daily consumption) diet made up of vegetables, fruit, nuts, legumes, whole grains, and fish has been shown to decrease inflammation when compared to current Western dietary patterns. By following this diet, individuals normalize the body’s inflammatory state as the immune system reduces the production of pro-inflammatory cytokines such as interleukins-6 (IL-6), IL-8, and TNF-α, while at the same time increasing the synthesis of anti-inflammatory cytokines such as IL-10. Furthermore, the reduced consumption of red meat, eggs and dairy products been shown to decrease systemic levels of TMAO, a molecule equally bad for our cardiovascular health as low density cholesterol. TMAO is generated by the sequential actions of certain gut microbes and the liver.
By increasing the ratio of fruits and vegetables in one’s diet along with the benefits of extra virgin olive oil, nuts, fiber as well as increasing the consumption of bioactive compounds such as omega-3 fatty acids, micronutrients, lycopene and polyphenols, the Mediterranean dietary interventions is able to reduce the risk of CVD.
“The European Society of Cardiology (ESC) and American Heart Association Nutrition Committee strongly endorse the daily consumption of multiple servings of both fruits and vegetables in order to reduce CVD risk.”
These suggestions are based on epidemiological studies and meta-analyses demonstrating that a higher intake of fruits and vegetables were strongly correlated with reduced adiposity and systemic inflammation in the body. Additionally, several studies and meta-analyses revealed the anti-inflammatory properties of olive-oil-rich diets. Extra virgin olive oil (EVOO) is an important component of the Mediterranean diet and has been shown to decrease markers of systemic inflammation in the body. EVOO consumption is associated with a decrease in C-reactive protein in the body and a reduced flow- mediated dilation of blood vessels in the heart. Moreover, EVOO’s high polyphenol content results in the gut microbes breaking them down into absorbable health-promoting metabolites. Another dietary intervention that can help to prevent the development of CVD is an increased consumption of nuts and seeds, also packed with polyphenols and healthy fats.
“A cross-sectional study …showed that a higher nut intake showed lower inflammatory biomarkers levels…”
By implementing dietary interventions, it is important to also incorporate beneficial nutrients that could enhance the anti-inflammatory effects of a Mediterranean diet. Numerous studies have pointed towards the health benefits of increased dietary fiber intake. One of the primary mechanisms of dietary fiber to reduce systemic immune activation and to decrease blood levels of “bad” cholesterol is the production of short chain fatty acids like butyrate. Butyrate prevents intestinal absorption of cholesterol and is created by the gut microbes from the ingestion of dietary fiber. In one experiment that examined the effects of fiber on cholesterol, authors reached the conclusion that the mechanism by which fiber lowers cholesterol is that it leads to increased micelle stabilization and enlarged particle size. Increased LDL-ApoB 100 turnover was exhibited in this study, thereby upregulating LDL receptors in the liver, which led to faster clearance of cholesterol. Since this study, several others have demonstrated similar results demonstrating the hypocholesterolemic effect of fiber, which could be important in attenuating atherosclerotic disease burden and ultimately decreasing CVD risk.
“…dietary fiber decreases the glucose absorption, and down-regulates the expression of oxidative stress related cytokines or the inflammatory response mediated by gut microbiota exposed to fiber…”
Likewise, bioactive compounds enriched in the Mediterranean diet, such as omega-3 fatty acids, short chain fatty acids, lycopene, and polyphenols play an important role in reducing inflammatory and oxidative stress biomarkers and in turn, the development of CVD. Meta-analyses demonstrate reported reduction in serum triglyceride levels in individuals of daily omega-3 consumption, promoting improvement in lipid and lipoprotein profiles that allow for greater expression of pro- inflammatory markers. Moreover, lycopene (an unsaturated carotenoid that is present in red- colored fruits and vegetables, such as tomatoes) has shown to improve the metabolic profile by imparting cholesterol synthesis while also suppressing basic inflammatory mediators such as reactive oxygen species (ROS). Lycopene is found in foods such as papaya, watermelons, and tomatoes. Lastly, polyphenols are bioactive compounds found in most fruits, vegetables, black and green tea, coffee, EVOO, chocolate, nuts, seeds, as well as herbs and spices. Microbial polyphenols metabolites play an important role in modulating the inflammatory response in the body and fighting against the development of heart disease. As explained in detail in The Gut Immune Connection the gut microbes are able to break down the large dietary polyphenol molecules into absorbable health-promoting metabolites that benefit various cells within the brain gut microbiome system, in addition to their widespread health benefits.
Overall, an extensive literature has shown a distinctive relationship between dietary choices and CVD risk. Although it may be challenging to make sweeping dietary changes from the Standard American Diet, smaller more sustainable additions of elements of the Mediterranean diet can lead to lasting habits that may lower the risk of CVD.
Chloe Arzy is a recent graduate from the University of Southern California where she earned her Bachelor of Science in Business Administration. She complemented her studies by receiving her Integrative Nutrition Health Coach certification from the Institute of Integrative Nutrition (IIN). She enjoys volunteering at Cedars Sinai Medical Center in the Advanced Heart Failure unit.